I'm curious how people store their PA gear for optimum organization, and easiest load-in/load out.

I keep all cables, mics, DIs, and other small items in 2 bags. 1 bag is gig essentials, and the other bag contains spares. I try hard to make sure that nothing leaves the essentials bag unless it's at a gig. The goal is to just grab the 2 bags and go, without any hunting and gathering. I also have speaker cabs, stands, lights, mixer, etc. in the basement. The pain is that I have to carry everything in through the back and down a flight of narrow stairs, and I'm usually parked on the street. I'd love to figure out a better way.

PA gear is stored in the garage, as well as my bass cabs. The PA cabs are on a furniture dolly. I have an 8 space rolling rack case where the PA amp resides, and there is enough room in there to put a couple bags with all the cables (and spares) inside. All I have to do is roll it all out to the truck and pack it accordingly.

Boxes. Flightcases, to be specific, have turned out the best thing. No wonder professionals all over the globe use them.
There's one for the cables, one for the mics, and so on. Way easier to store away if it's in a box format and stackable.
When not in use, the PA is in the rehearsal room. That is ground floor and you can park the car right in front of the door. And the room has a better insurance than my home ;-)

Cables go in a rolling tool bag from Home Depot. It makes them easy to find. Mic stands go in a cheap duffle bag from a sporting goods store. The bag doubles as a bag to haul drum hardware, since I don't use both at the same time. The big speakers live in a storage garage, and I use a refrigerator hand truck to move them. The board and amplifiers live in a rolling rack I built for them. The rack also has a power conditioner and a couple drawers for whatever needs to go in there at the time. Not much for now. That rolling rack also lives in a storage garage. The monitors and small PA speakers stay in my basement, along with a smaller powered board that gets used for smaller venues. The big speakers are way too big for sanity, but they are nice to have when you need both visual and sound volume. They are paid for, the garage would be rented anyway, and the trailer is paid for, so there's no reason to get rid of them. All of the equipment works as a modular thing - the small PA speakers get used as monitors with the big PA, for example.

Security? The trailer got broken into a while ago. They stole a folding aluminum motorcycle ramp, which pissed me off. They also cut up the locking hardware pretty badly. My guess is the (probably stolen) bolt cutters they used to trash the trailer's door latch cost a lot more than what they got for the aluminum ramp. Buying the hardware to fix the latch probably cost more than they got. The ramp was probably worth a couple dollars for scrap, max. They couldn't sell it for anything except scrap. I used it regularly, but it's not irreplaceable, and I haven't missed it much, but it still irritated me a whole lot. After that, I have not locked the trailer nor put anything in it unless it's being moved right then.

Band leader owns all PA. We have a rolling rack that houses snake, extension cords, mic cables etc and our Line 6 mixer. We have 2 powered JBL subs each in their own rolling cases and two powered JBL tops that both share a rolling flight case. 2 powered EV monitors are in their own smaller flight case. I bring my own powered monitor and gear and the drummer brings his gear, portable riser, powered monitor, his own mic stands, mics, cables and he also brings a pair of LED light trees. Guitar player has IEM's that he uses and his gear. Everyone's respective gear stays at each persons home. We pretty much just rent a small uhaul trailer each weekend for gigs and the BL is in the midst of getting a custom built trailer spec'd out. We load in and out the day of the gig so nothing is in jeopardy of being stolen from the trailer or anything like that. After a few setups we got it fine tuned and can be up and running pretty quickly.